The crushing strength of the St. Clair marble varies from 6,260 to 9,790 pounds per square inch and the absorption ratio from 1:209 to 1:425. The specific gravity varies between 2.682 and 2.707, weighing from 167.60 to 169.17 pounds per cubic foot. Independence Marble Company, Batesville, Ark. 1. 2. Bibliography of Marble in Arkansas 1890 Hopkins, T. C., "Marbles and Other Limestones."-Annual Report of the Arkansas Geological Survey for 1890, Vol. IV, "Marbles." Obtainable from Arkansas Geological Survey, 447 State Capitol Building, Little Rock, Ark. 1891 Hopkins, T. C. "Topographic Features of Arkansas Marble (Abstract)."-Bulletin of the American Association for the Advancement of Science, Tr. 39, pp. 247-248, obtainable from American Association for the Advancement of Science, Smithsonian Building, Washington, D. C. 1909 2. Anonymous, "Batesville Oölitic Marble."-Stone, Vol. 29:345-346. Illustrated. New York, January, 1909. Dolomite Dolomite is a magnesian limestone and is little used in Arkansas except for structural purposes. Some of the dolomite is crystalline and could be used as a decorative interior stone. Dolomite from Hardy, north Sharp County, takes a high polish and is of a red brown color. The dolomite beds of north Arkansas are probably between 2,300 and 2,600 feet thick along the northern border of the State in Fulton County. Dolomite is used (1) in the manufacture of dead burned dolomite refractories, (2) as a flux in smelting iron, steel, etc., (3) in the manufacture of high magnesian lime, (4) as agricultural limestone, (5) as crushed stone, rip-rap, and rubble, (6) as a building stone, (7) when pulverized, as a substitute for whiting, (8) as stucco dash, concrete block facing, etc. The dolomites of Arkansas are confined almost entirely to the Powell and Cotter formations of Lower Ordovician age which are found only in northern Arkansas. The location of these deposits is shown on the accompanying map and the deposits are shown in more detail on the geological map in the back of this book as the exposed outcrop of Ordovician, Silurian, and Devonian rocks in north. Arkansas. Production Included under "Granite." Producers Fisher Lime & Cement Company, Williford, Sharp County, Ark. For bibliography of Dolomite see "Bibliography of Marble,” above. CHALK (See also "Cement Materials" and "Mineral Fertilizers") Composition. Chalk is essentially a calcium carbonate rock and is therefore in the limestone class of rocks. It is composed chiefly of the skeletons of microscopic limey organisms and its distinguishing characteristics are its light color, which is usually gray, cream or white, and its soft, friable qualities. The composition of the chalk from the different chalk areas of Arkansas is given under the discussion of each area. Uses. Chalk is used in the manufacture of burnt and unburnt lime products, such as Portland cement, plaster, fire brick, chemicals, soap, bone ash, artificial gas, paper, pottery, pottery material. egg preservatives, tanning materials, and in the dehydration of alcohol. It is also used in the treatment of acid soils. Occurrence. The accompanying map shows the distribution of chalk and chalky clays or marl in Arkansas. The Arkansas chalk is of Upper Cretaceous age and is connected with the Austin chalk beds of Texas which extend from Texas eastward into Arkansas and eventually disappear in the extreme southeastern portion of Howard County. These chalk lands include chalks, marls, and chalky marls of various composition and cover portions of Clark, Nevada, Pike, Hempstead, Howard, Sevier and Little River Counties. There are, however, only three outcrops of any size in Arkansas which may be classified as true chalk. These are: (1) The Rocky Comfort or Foreman deposit, (2) the White Cliffs deposit, and (3) the Saline Landing deposit. These lie in Little River and Howard Counties. 2 3 1 No. The Rocky Comfort or Foreman deposit covers an area of about 1,500 acres. The true chalk is at least 100 feet thick and may be considerably thicker and it is estimated that the quantity of true chalk available in this area is approximately 500,000,000 tons. extends southwest from Rocky Comfort, including portions of Sections 21, 27, 28, 29, 32 and 33, all in Township 12 south, Range 32 west. This area has a gently rolling topography and consequently there are no thick outcrops of chalk. The bed has a gentle dip to the southeast, as have the other chalk deposits of Arkansas. The following are three analyses of chalk from the Rocky Comfort area:* The White Cliffs deposit covers an area of approximately 600 acres and the thickness of the true chalk is probably about sixty feet, lying in Sections 25, 26, 35 and 36, Township 11 south, Range 29 west, and Sections 30 and 31 in Township 11 south, Range 28 *J. H. Taff, "Chalk of Southwestern Arkansas."-U. S. Geological Survey, Twentysecond Annual Report, Part III. Chalk Cliffs at White Cliffs, Arkansas Carbonate of Mag nesia, MgCO3 |